Display screen or portion thereof with a graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with a graphical user interface showing a first embodiment of the new design; and

FIG. 2 is a second embodiment thereof.

FIG. 3 is a front view of a third embodiment thereof.

FIG. 4 is a front view of a fourth embodiment thereof; and,

FIG. 5 is a front view of a fifth embodiment thereof.

The outermost solid line in the FIGS. illustrates a portion of a display screen and forms part of the claimed design.

The broken line showing of portions of the graphical user interface is included for the purpose of illustrating portions of the article and forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface, as shown and described. 